A few seconds later, when Warnell refused to put his hands behind his back, officer Mulhollan pushed him to the ground.

Image source: WFAA-TV

Image source: WFAA-TV

Watch the footage in WFAA-TV's report:

"All of a sudden, he just bum-rushed and knocked me down, and almost hit my head, and started to wail on me," Warnell told WFAA-TV of the incident over which he is now suing the police department.

KBMT-TV noted that police Capt. C.A. Stephenson wrote in an internal memo that the video calls into "question how [officer Mulhollan] responds in incidents where his actions are questioned as well as his ability to control his aggression when his authority is questioned."

"Even after being shoved to the ground and being struck in the face, Warnell was never abusive or threatening, but was still wanting to know why he was treated the way he was when he was only trying to find out what was happening on his property," the memo continued.

"The only thing I can tell you, if I was in a different neighborhood, a different color, and I came outside on my property and inquired what was going on, this never would have happened," Warnell told WFAA.